For online games, I recommend multiplayer online battle arena mobile games like mobile legends and Garena's Arena of Valor. I am sure you are going to have fun with these games, why, because these games are several game genre packed. First, strategy, teamwork is required for you to win battles, you will be able to interact with real players, real people in real time. Second, action, every hero's skill is unique and there are lots of colorful and cool heroes to choose from. You can fight one on one with a player or can be the usual mode which is 5 vs 5. There are lots of things that can be done in these games. I assure you, you'll get hooked to these moba games and you won't get bored.
Moreover, for offline games, I suggest, you download Dungeon Quest. I played this game last year for about 9 months. It is a great time killer. You can choose the type of hero you want, can be a marksman, a warrior or a wizard. You can customize your items here. Items can be collected throughout the game of course. One thing that can amaze you about this game is the good graphics.